Quality is always more important than speed.
Maintainability is also more important than speed.
If one person delivers a solution that doesn't scale, crashes frequently, and is impossible to maintain, he's actually less productive than someone who takes a few more days (or weeks, depending on project size) to deliver something that is rock stable, easy to maintain, and scales well.
Sadly many performance reviews still look only at lines of code produced per time
unit (or similar broken definitions of performance) because that's easy to measure.